
/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.graphics;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.math.Matrix4;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.math.Vector3;

/** A camera with orthographic projection.
 * 
 * @author mzechner */
public class OrthographicCamera extends Camera {
        /** the zoom of the camera **/
        public float zoom = 1;

        public OrthographicCamera () {
                this.near = 0;
        }

        /** Constructs a new OrthographicCamera, using the given viewport width and height. For pixel perfect 2D rendering just supply
         * the screen size, for other unit scales (e.g. meters for box2d) proceed accordingly.
         * 
         * @param viewportWidth the viewport width
         * @param viewportHeight the viewport height */
        public OrthographicCamera (float viewportWidth, float viewportHeight) {
                this.viewportWidth = viewportWidth;
                this.viewportHeight = viewportHeight;
                this.near = 0;
                update();
        }

        /** Constructs a new OrthographicCamera, using the given viewport width and height. This will create a camera useable for
         * iso-metric views. The diamond angle is specifies the angle of a tile viewed isometrically.
         * 
         * @param viewportWidth the viewport width
         * @param viewportHeight the viewport height
         * @param diamondAngle the angle in degrees */
        public OrthographicCamera (float viewportWidth, float viewportHeight, float diamondAngle) {
                this.viewportWidth = viewportWidth;
                this.viewportHeight = viewportHeight;
                this.near = 0;
                findDirectionForIsoView(diamondAngle, 0.00000001f, 20);
                update();
        }

        public void findDirectionForIsoView (float targetAngle, float epsilon, int maxIterations) {
                float start = targetAngle - 5;
                float end = targetAngle + 5;
                float mid = targetAngle;

                int iterations = 0;
                float aMid = 0;
                while (Math.abs(targetAngle - aMid) > epsilon && iterations++ < maxIterations) {
                        aMid = calculateAngle(mid);

                        if (targetAngle < aMid) {
                                end = mid;
                        } else {
                                start = mid;
                        }
                        mid = start + (end - start) / 2;
                }
                position.set(calculateDirection(mid));
                position.y = -position.y;
                lookAt(0, 0, 0);
                normalizeUp();
        }

        private float calculateAngle (float a) {
                Vector3 camPos = calculateDirection(a);
                position.set(camPos.mul(30));
                lookAt(0, 0, 0);
                normalizeUp();
                update();

                Vector3 orig = new Vector3(0, 0, 0);
                Vector3 vec = new Vector3(1, 0, 0);
                project(orig);
                project(vec);
                Vector2 d = new Vector2(vec.x - orig.x, -(vec.y - orig.y));
                return d.angle();
        }

        private Vector3 calculateDirection (float angle) {
                Matrix4 transform = new Matrix4();
                Vector3 dir = new Vector3(-1, 0, 1).nor();
                float rotAngle = (float)Math.toDegrees(Math.asin(Math.tan(Math.toRadians(angle))));
                transform.setToRotation(new Vector3(1, 0, 1).nor(), angle);
                dir.mul(transform).nor();
                return dir;
        }

        private final Vector3 tmp = new Vector3();

        @Override
        public void update () {
                projection.setToOrtho(zoom * -viewportWidth / 2, zoom * viewportWidth / 2, zoom * -viewportHeight / 2, zoom
                        * viewportHeight / 2, Math.abs(near), Math.abs(far));
                view.setToLookAt(position, tmp.set(position).add(direction), up);
                combined.set(projection);
                Matrix4.mul(combined.val, view.val);
                invProjectionView.set(combined);
                Matrix4.inv(invProjectionView.val);
                frustum.update(invProjectionView);
        }
        
        /**
         * Sets this camera to an orthographic projection using a viewport fitting the screen resolution, centered
         * at (Gdx.graphics.getWidth()/2, Gdx.graphics.getHeight()/2), with the y-axis pointing up or down.
         * @param yDown whether y should be pointing down
         */
        public void setToOrtho(boolean yDown) {
                setToOrtho(yDown, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        }
        
        /**
         * Sets this camera to an orthographic projection, centered
         * at (viewportWidth/2, viewportHeight/2), with the y-axis pointing up or down.
         * @param yDown whether y should be pointing down.
         * @param viewportWidth
         * @param viewportHeight
         */
        public void setToOrtho(boolean yDown, float viewportWidth, float viewportHeight) {
                if(yDown) {
                        up.set(0, -1, 0);
                        direction.set(0, 0, 1);
                }
                position.set(viewportWidth / 2.0f, viewportHeight / 2.0f, 0);
                this.viewportWidth = viewportWidth;
                this.viewportHeight = viewportHeight;
                update();
        }
}